Art of burning fuel



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J. M. scHuTz ART OF BURNING FUEL Filed sept. e, 1923 3 Sheets-snee: 2

/NVENTOR Jan. 31, 1928.

J. M. SCHUTZ ART OF BURNING FUEL' Filed Sept. 6, 1923 3 Sheets-Sheet. 3

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b1] A TTORNE Y- Patented Jan. 3l, 1928.

UNITED ASTATES s 1,657,698 PATENT orner..

JOSEPH MARTIN SCHUTZ, 0F CHICAGO, ILIJIN 01S, ASSIGNOR, BY MESNE ASSIGNMNTS, TO CHARLES GILBERT HAWLEY, 0F CLEVELAND, OHIO.` l

ART or BURNING FUEL.

Application led September 6, 1923. `Serial No. 661,163.

My inventionrelates to the combustion of fuels and has special reference to the burning of ulverulent or comminuted coals of all kin s, ranging from woodv and peat, through the lignite and bituminous groups, and including cokes and anthracite coals.

My purpose in this invention is to provide a simple, safe, efficient and easily controlled continuous process of burnin"` fuel for the rapid production of heat at Iiigh temperatures; and, a particular object is to speed up and ensure the better working of the process of combustion that is described and claimed in Patent No. 1,306,233 of June 10, 1919. It will presently become apparent that the old and the new processes have much in common. Both are conducted within an upright annulus or burner proper that `is open at the top, and which is closed at the bottom save for a comparatively small slag discharge opening.

In the older process both the air and the fuelV are introducedtangentially at the top of the annulus and whirl against the inner walls thereof and downward toward its bottom, meantime taking fire, and the products ultimately react and return upwardly along the central axis; the flame rising from the lower part of the annulus and discharging through its open top. a

In my present improvement only the air is introduced tangentially at the top of the annulus. The coal is introduced close to the bottom, or as I herein call it, the circular hearth. The active combustion is initiated on such bottom or hearth and is there completed to the point of fuel decomposition and the melting out or separationof the fuel ash. y i

In form, the resultant tire is `much the same as that derived from the patented process. but is greatly accelerated and intensified; and is sharply localized on the bottom or hearth of the annulus; the means to that end being the important new step of highly preheating the entering air before it reaches the fuel particles in the burner. This preheating of the air, I accomplish within the burner itself. i

The whirling of the air and gases on the hearth very definitely holds back the particlesof coal and coke from the central ash opening, allowing only the-liquefied ash to `is relieved from the duty control of the` entering air and in respect to the discliargingflame.

In this invention, as contrasted with the old, the whirling column of air. (generated byw the tangential twyers) vwhich drives downward onto'the periphery of the hearth, and burden of spreading and holding the fuel particles on the vertical walls of the/annulus, leaving said walls free to perform, in conjunction with the outgoing central body'of flame, the new and important oiice of preheating the supplied air to a tem erature approximating that of the flame. nd thus before the air reaches the fuel on the hearth it is preheated to al temperature so high as to ensure the almost instantaneous combustion of the fuel at the moment of admixture therewith;` markedly hastening the performance of the complete process; or reversely, greatly increasing the capacity of a burner or annulus of given size.

Still further objects and features of the are respectively vertical and horizontal sectional views of an apparatus or fuel burner that I have devised for the workingfof this invention or process.y Fig. 1 is a section on the line 1`1 of Fig. 2, and Fig. 2a section on the irregular line 2-2 of Fig. 1. Figs. 3 and 4 are vertical and horizontal sections on respectively indicated planes or lines (3-3) l and (f1- 4) illustrating the best form of apparatus that Ihave thus far invented for carryingoutmy novel process and particularly designed to enable the use of an important step and efl'ect not so well provided for in the burner of Figs. l and 2. The

particular structurel illustrated kin Figs.` 3

and 4 is more fully'described and is separately claimed in my companion application S. N. 661,164 entitled Fuel burners, of even date herewith.

Referring to Figs. 1 and 2, the

be substantially circular in horizontal cross section. 'It is preferably composed of a refractory material such as lire. brick, and, is

`vertically disposed annulus or burner will be seen to.

preferably constructed within andprotected by an imperforate metal shell 2. The annulusproper comprises the circular or cylinder wall 3', plus the bowl-like bottom .or hearth 4, before mentioned. The slag discharge hole 5 is located at the center of the hearth. 6 represents the large flame discharge opening at the top of the annulus. The only real top portion that the annulus need have comprises the overhangino' air-` llso of abutment ledge or ring refractory material.

Directly above the hearth 4, I introduce the comminuted or pulverulent coal or other fuel to be burned, using by reference a plurality of twyers 8 or supp y pipes for the purpose. For sake of clearness, and 1t being understood that the comminuted fuel may be easily introduced through the agency of air blasts through the pi es 8, I have shown the twyers 8 in tangentla `relation to 'the perlphery of the hearth. Thus positioned the twyers have an initial effect 1n circumferentiall distributing or spreading the fuel on -the hearth, but the fuel may be introduced radially throu h the walls of the hearth or in any other esired manner, for as hereinaftervexplained the force of the yvhlrhng supply of combustion supportlng a1r 1s amply suiicient to uniformly distribute the fuel articles about the periphery of the hearth. ost conveniently the hearth takes the form of a shallow bowl which has sufficient height to let the fuel through openings slightly above the floor of the hearth, where the fuel ash is liberated and liqueied. In someI cases a part of the air required 7, preferably a for the combustion of the fuel ma .be in` troduced into the lire chamber 9 a ove the burner, such air feed being determined according to the kind of fuel burnedy and the degree of combustion re uired in the burner.` For the urposes of t is description the whole or t 1e greater art ofthe air required for combustion may e treated as being introduced through the burner. It is introduced in such manner as to form a downwardly moving and rapidly whirling hollow column.

The air enters the burner under a pressure considerably reater than that in `the fire chamber 9 an its introduction in the whirling manner4 described may be accomplished in various ways and by various means. The simplest means `comprise the overhanging ledge or abutment ring 7 and a plurality of tan ential air twyers 10 which penetrate the wa of the burner directly beneath the ledge 7. The pressure air, in the structure villustrated, is supplied from a 'suitable source through the pressure trunk 10 and thus freely enters all of the twyers 10 with substantially uniform pressure and velocity. Entering thus, the streams of air from the twyers encounter the cylindrical wall 3f of the burner and the centrifugal force set u causes the streams to press against that walli As egress upwardly 1s blocked by the abutment ledge 7 the whirling blasts of air are forced to descend toward the bottom of the burner, describin spiral paths that may be likened to the ow-pitched threads of a screw. Thus the air supplied for the combustion'of the fuel is forced to make many turns within' the burnerand to travel from top to bottom thereof before comin in contact with the fuel on the hearth. t beinV understood that the mixture of fuel is ignite within the burner, it will also be understood that very uickly a rotating llame of, large volume andl great intensity 1s oenerated and continuously maintained on the bottom of the burner and at its axis. That bottom being closed, except for the small'slag hole 5, the flame of necessity finds escape at the top of the burner through the large opening 6. The whirling motion of the air and gases within the burner is depictedby the spirally formed set of arrows in Fig. 2. The downward sweep of the air within the burner and the upward sweep of the flames and gaseous products of combustion are well represented by the two sets of arrows in Fig. 1. The outward throw or whirling of the flames and gases at the mouth or to of the burner, as depicted by these arrows, 1s caused by the terrific whirling of the products within the burner, which whirling and resultant centrifugal action, persists as the flame emerges fromv the top of the burner.

Having thus visualized the presence of combustion and the action of the upwardl moving body of flame within the burner, 1t will now be apparent that the freshly entering air from the twyers 10 moves circu larly and spirally within the burner for a great distance and that throughout such travel the thin wall of air is directly in the presence of and exposed to the central body of the flame. Some of the supplied air doubtless more or less directly enters into combination with the richer products of combustion upon the exterior of the whirling central body of flame, but the greater quantity continues to the bottom and receivesa full quota of heat both from the combustion golng on in they burner and the hot walls. Hence for all practical purposes it may be said that before it reaches the bottom of the burner the air is heated almost to the temperature of the flame itself. It follows that the fuel particles attacked b air at such temperatures are consumed a most instantly, passing through all of the stages of decomposition and combination with almost explosive rapidity at the bottom of the burner or furnace. Obviously the walls of the burner normally are kept at a white heat, incandescent, and in the presence of `these walls and the direct heat of the combustion, the freshly'entering fuel is brought to a high temperature before the highly preheated air is admixed therewith. In this from the combustibles. Due to its weight and viscosity the molten ash, or as it should now be termed, the slag, adheres to the floor of the hearth and as it accumulates, flows to the center of the burner and discharges through the central opening 5.

Attention Ais called to the small arrows 5 in Fig. l. These are intended to represent the working of the burner or furnace at such internal pressure as will cause a slight lapping downward of flame at the mar in of the slag hole, this being done to avoi pos-` sibility of the chilling of the slag thereon, which if permitted would ultimately close the opening and require that a new opening be punched or made at the center of the hearth. The operation of the burner at such internal pressures may be disregarded when the slag opening communicates with a tightly closed chamber that prevents an upward flow of cold air through the slag o ening. Such a flow would chill or solid-k i y the slag and is to be avoided.

My invention comprehends the varying of the distance between the air twyers and the coal twyers in relation or proportion to the diameter of the burner, to either increase or decrease the time ofthe exposure of the air to the preheating action of the burner walls and its contentr of flame. It is proper, to call attention to the regulation of tem erature for the reason that some grades o coal contain ashes which fuse at ver `low temperatures and for such coals it `1s desirable to limit the temperature at the bottom ofthe burner and thereby prevent the va orization of the ash, which notwithstanding the forcible centrifugal action to which all of the products are subjected might result in vpermitting such vapors. to be discharged with the flame and to be thereafter condensed by contact with relatively cool surfaces in or about the lire chamber 9.

Further it should be noted that `as the diameter of the burner is increased in relation to the distance between the air and fuel twyers, the burning products are allowed freer egress. This lessens the time that a given fuel particle and its products remain in the burner and hence affects the ultimate temperature therein. By proportioning the burner height and depth it easily may be adapted to any fuel; and likewise, may be adapted to the burning of any given quality of fuel within a given time. The temperature within the furnace or lburner is also to be controlled by varying or proportioning lthe supplies or feeds of air and fuel.

For the purpose of further indicating that my inventionis not limited to a specific structure, I call attention tothe fact that by enlargin the burner toward the bottom. more or fless as shown in Fig. 1,the need of the overhanging ledveor air-abutment ring 7 may be minimize `and if desired the use of such a distinct abutment may be entirely avoided. The enlargement of the furnace toward the bottom affords the relief in that direction as opposed to the upward direction, which latter would ermit the air to escape fromv the burner wlthout first being .admixed with the fuel ony the hearth.. In

practically all these burners some of the air may escape directly at the top, but as before indicated it is not necessary that all of the air. shall descend to the bottom of' the burner. y y

The crushed or comminuted coal supplied to the hearth of the furnace always contains many fine particles. To start the process into operation y:it is only necessary to apply a torch or kindling of any suitable kind within the bottom of the burner. Then the air blast is started through the top twyers. Instantly an energetic fire is organized, and then the streams of fuel are admitted through the feed twyers 8. The addition of the fine fuel to the fire further augments the latter and within a few minutes the inner walls lof the furnace are brought to incandescence and a flame body of size and temperature sufficient to take care of the full supply'of fuel is established.

VI shall now refer to Figs. 3 and 4 of the drawing. y i l It is ldesirable that the air which enters the. burner vshall be brought to a high temperature as quickly aspossible- From the standpoint of a burner or furnace, which shall be adapted for use within a limited space, it is desirable that thedepth of the burner shall be reasonably shallow. Again, it is desirable that the air which enters the burner. shall be caused to Whirl therein with the least obstruction to its movement and shall bev permitted to attain the highest whirling `velocity consistent with the pressure at which it enters, to the end thatsuflicient centrifugal force shall be developed on the hearth to surely retain the fuel at the periphery thereofand thus prevent loss of fuel eithervdownward through the slag hole or upward with the central body of flame. For the concurrent attainment of these objects and conditions, in carrying out my process, I preferably employ an air twyer construction which ydivides the air Supply into a great number of thin sheets or streams that are disposed tangentially to the body of 'the burner and are 4substantially parallel to the axis thereof. The thin streams or sheets thus entering the burner la one over the other, and as they circle within the burner constitute an annulus moving downward upon the hearth. The organization and preservation of the supplied air in this form of a thin walled annulus, obviously serves to ideally present the :tir for the rapid reception of the heat of the central column of flame, the heat being received directly therefrom and from the hot surfaces against which the incoming air' moves. The rapid heating of the air being assured, it follows that its vertical movement or path within the burner, maybe shortened, and the burner as a whole may be proportionately of less depth than a burner of the kind shown in Figs. 1 and 2. And, as an exact centrifugal control of the whirling air must needs result in'causing the lower end of the continuous column of air to descend upon the hearth at a maximum whirling velocity, it follows that the particles of coal on the hearth will not only hc certain to be set into rotation thereon, but that such movement wll be maintained at velocities that develop in such particles sufficient centrifugal force to hold them at the peri hery of the hearth, against the inward pus iing forces of the air and gases that react inwardly and upwardly from the hearth; and thus the escape of fuel at the slag hole is prevented.

For the reasons here explained the rotating organization of the described thin walled annulus or hollow column of air constitutes a very desirable step of my process.

Figs. 3 and 4 illustrate one such twyer construction and the effect which it has upon the general construction of the burner or furnace. This twyer construction comprises a ring or annulus that is made up of a large number of upright metal blades, vanes or flights, 11, separated by narrow slits or spaces 12; all inclined or curved in the same direction; and all, as nearly as Kfeasible, at true tangents to the inner pe- -riphery of the ring which they constitute.

Practically the height of the vanes and hence the height of the tangential twyer ring as a whole, is or may be substantially the same as the height of the surrounding pressureair trunk 13. The latter is of sufficient capacity to insure a substantially uniform pressure at each of the elongated narrow "slits or twyers proper 12, and, of necessity, the air passing inwardly through the twyers is organized into the described thin walled air column whirling at such velocity and with such centrifugal force as to bank against the inner periphery of the twyer rin and to forcibly seek escape at the top an bottom thereof. At the top, escape is cut off by the overhanging abutment ring or ledge 14. At the bottom its escape is permitted, for there the descending whirling column directly enters the bowllike hearth 15 and through many whirling motions finally approaches the axis of the burner and finds relief upwardly through the open top of the burner; or in other words, is per mitted to escape upwardly through the continuously maintained hollow annulus of air at the twyers. By these steps the above defined purposes are accomplished with the desired effects.

The fuel is admitted to the bowl 15 through one or several fuel twyers 16, which as suggested in Figs. 3 and i ma be disposed radially or in any other dcslred relation, so long as the fuel is continuously fed upon the. hearth. The actual feeding of the fuel may be done by blasts of air or other gas in the twyer pipes, or it may be fed by any other force, including inspiration and the forces of any suitable mechanical feed mechanism. As before stated, it is only necessary to deliver the fuel upon the hearth. From that moment, it is carried forward and properly distributed by the whirling air and gas within the burner.

My invention is not strictly limited to the burning of coal, but also includes the burning of various fuel oils and gases; both to the end that the process may be worked alternately with such fuels, and to the end that the latter may with convenience be used for startin or kindling the coal fire on the hearth. I iave not herein shown large gas twyers such as may be employed at the inargin or periphery of the hearth, but as representing both oil and gas feeds have depicted the use of the additional fuel twyers 17, the same appearing in both Figs. 3 and 4. 0bviously, any suitable means may be employed to supply or feed the fuel to such alternative or additional twyers.

In other respects, the process as )racticed in a burner of the construction o Figs. 3 and 4, does not differ from the practice with burners of the kind shown in Figs. 1 and 2; and therefore it seems unnecessary to here repeat the description of the elementary steps of the process as specifically related to a shallow burner of the kind shown in Figs. 3 and 4.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. The herein described improvement in the art of burning fuel, that consists in organizing a vertically extended thin walled hollow column of air in whirling downward motion and continuously maintaining the same by the supply of resh airthereto in tangential strealns of sheet-like form entering the uper part of said column and substantially paralleling its axis, injecting fuel at `the lower end of said column for combustion lill) *consists in organizing a vertical ing downward motion and continuously` maintaining the same by the supply of frcs air thereto in tanffentlal streams of sheety like form substantlally paralleling itsl axis,

in 'ectin fuel at the lower end of said column or combustion with the air arriving at that point in highly pre-heated condition,

maintaining ignition and prolonging the combustion u wardly within said column and draining t e ash from the foot of said column.

3. The herein described improvement in the art of burning fuel that consists in-form- 20 `ing and feeding a hollow whirling column of air downward in the resence of a flame axially within said hol ow column, feeding fuel to the lower downward moving part of said column and admixing the same with the '25 then heated air, igniting the mixture from said axial flame and ynermitting the burning mixture to escape a 'ong the axis of said column.

JOSEPH MARTIN SCHUTZ. 

